1. Field of the Invention
The invention relates to a one step method for the preparation of alkylphenols from phenol and the corresponding olefin. More particularly it relates to a one-step method for preparation of alkyl phenols by reacting phenols and the corresponding olefins over acid treated montmorillonite clays. The method is especially effective in the synthesis of the most desirable para-alkyl phenol, for example, para-nonylphenol, from phenol and nonene.
2. Description Of The Related Art
It is known in the art to prepare higher molecular weight alkylphenols, such as p-tert-octylphenol, p-nonylphenol and dodecylphenol by alkylating phenol with diisobutylene, propylene trimer and propylene tetramer, respectively, under acidic conditions. Nonylphenol, in particular, is used as an intermediate for surfactants, as well as antioxidants and lube oil additives.
In "Bisphenol A and Alkylated Phenols", SRI PEP Report No. 192 (Dec. 1988)., page 4--4, it is reported that it is known in the art to prepare various alkylphenols by acid catalyzed reactions of phenols with various olefins. These alkylphenols may include p-tert-butylphenol, p-isopropylphenol, p-sec-butylphenol, p-tert-octylphenol, nonylphenol and dodecylphenol. The alkylation reaction takes place at or near atmospheric pressure in the presence of an acidic catalyst such as a mineral acid, a Lewis acid (e.g. boron trifluoride) or a cation exchange resin (e.g. styrene-divinyl benzene resin). The acid catalysts lead to predominantly para-alkylated phenol when the para position is available. Generally a molar ratio of phenol to olefin of 1.5-3:1 is desired to minimize the yield of dialkylphenols.
U.S. Pat. No. 4,198,531, to BASF, discloses a process for continuous manufacture of p-alkylphenols by reacting phenol with olefin at 70.degree.-40.degree. C. in a fixed bed of an organic sulfonic acid cation exchange resin.
A Lewis acid, Bronsted acid or aluminum chloride catalyst is employed in U.S. Pat. No. 4,096,209 to Ciba-Geigy to prepare a phosphorylated butylated phenol/phenol ester mixture.
In U.S. Pat. No. 2,684,389 to Gulf R & D a phenol and mono-olefin are mixed in the presence of a silica-aluminum adsorbent catalyst at 137.degree. C. A silica-alumina catalyst is also employed in U.S. Pat. No. 3,876,710 to Hitachi to produce PTBP from phenol and isobutylene.
A BF.sub.3 catalyst is used for the reaction of phenol and isobutene in British 1,294,781 to Hoechst where the product cooled to form crystals which are crushed before ammonia is added to remove the catalyst. British 1,249,571 is related.
In German Offen. 3,443,736 to Huels the catalyst is a sulfonated polystyrene ion exchange catalyst. U.S. Pat. No. 4,461,916, also to Huels, discloses a two-stage approach for producing p-tert-octylphenol using an acid ion exchange resin. U.S. Pat. No. 4,236,033 and U.S. Pat. No. 4,168,390 to Huels also disclose ion exchange resins, the latter comprising a LEWATIT.RTM. resin deactivated with Al.sub.2 (SO.sub.4).sub.3.
British Patent 2,120,953 to ICI discloses a process for producing nonylphenol by reacting diisobutene with phenol in the presence of a catalyst comprising fuller's earth with alkyl or aryl phosphate or phosphate ester.
U.S. Pat. No. 3,872,173 to Progil discloses the reaction of gaseous isobutene with liquid phenol in the presence of an acid-activated clay, again in two steps.
A highly acidic aryl sulfonic acid catalyst is employed in U.S. Pat. No. 3,932,537 to react phenol with isobutene under anhydrous conditions.
U.S. Pat. No. 3,422,157 to Union Carbide employs a cation exchange resin catalyst.
British Patent 1,314,623 to Union Rheinische Braunkohlen discloses an activated, acid-free bleaching earth catalyst.
In U.S. Pat. No. 4,260,833, to UOP, phenol and isobutylene are reacted at 250.degree. C. in the presence of a lithiated alumina catalyst. U.S. Pat. No. 3,929,912 discloses a more general alkylation of phenol and olefins in the presence of hydrogen fluoride and carbon dioxide.
An aluminum phenoxide catalyst is used for the orthoalkylation of phenol with butene-1 in French Patent 2,296,610, and U.S. Pat. No. 3,766,276, to Ethyl, as well as U.S. Pat. No. 3,933,927.
A boron trifluoride catalyst is used for the alkylation of phenol in U.S. Pat. No. 3,317,612.
Activated earth and phosphoric acid are used in a liquid phase transalkylation process in British Patent 1,444,935.
Acids are also useful for the condensation of phenol with acetone. Representative acids include an aromatic sulfonic acid (German Offen. 2,811,182 and U.S. Pat. No. 4,387,251), a volatile acid catalyst (U.S. Pat. No. 2,623,908), a strong mineral acid such as HCl or H.sub.2 SO.sub.4 (U.S. Pat. No. 2,359,242), hydrochloric acid (U.S. Pat. No. 4,517,387), H.sub.2 SO.sub.4 or HCl and 2-(4-pyridyl)ethanethiol (Japanese Kokai-57-118528), concentrated HCl (Japanese Kokai 60-38335) and hydrogen chloride (U.S. Pat. No. 4,169,211).
The use of clays as catalysts for selected applications is known in the art. In an article titled "Catalysis: Selective Developments", Chem. Systems Report 84-3, 239-249, section 3.4320, the unusual properties of smectite clays which make them of interest as catalysts are discussed. These compositions are layered and exhibit a 2:1 relationship between tetrahedral and octahedral sites In addition the combination of cation exchange, intercalation and the fact that the distance between the layers can be adjusted provide interesting possibilities.
An article by F. Figueras, titled "Pillared Clays as Catalysts", in Catal. Rev.-Sci. Eng., 30, 457 (1988) discusses methods of modifying clays and the effects of the modifications. At page 472, there is a discussion of the method of drying, i.e. air drying or freeze drying, which can affect the macroporosity of the resulting product and, as expected, the adsorption capacity. The author concludes the thermal stability of pillared clays can be improved to reach 800.degree. C. using information available with respect to intercalation and drying methods.
Figueras notes, page 481, that the acid strength of montmorillonites was found to be higher than that of Y-zeolites and, in the case of the clays, Bronsted acidity appears to be weaker than Lewis acidity. The author describes three kinds of acid sites known to exist at the surface of clay and suggests the coexistence of several types of acidity makes the localization of acid sites more difficult than in well-crystallized structures.
There is a review of the catalytic activity of pillared clays by T. Matsuda and E. Kikuchi, titled "Acidic Properties of Pillared Clays in Relation to Their Catalytic Behavior", in Proceedings of International Symposium on Acid-Base Catalysis, Sapporo, Nov. 28-Dec. 1, 1988. In Ch. 3.11 these authors observed Bronsted acid sites are responsible for isomerization whereas both Bronsted and Lewis acid sites can catalyze disproportionation. Other pertinent findings were that Bronsted sites are far more active than Lewis sites, however, studies would indicate an irreversible change of Bronsted acidity to Lewis acidity in the course of high temperature calcination, ibid, page 354. They concluded that cracking of a compound such as cumene, for example, depended only on the acidic properties, however disproportion activity was affected by the pore structure in addition to acidity. This was thought to relate to the fact that pillared montmorillonite had regular micropores while pillared saponite consisted of macropores. In addition saponite is tetrahedrally charged clay with Al cations substituting for Si cations. In montmorillonite, in contrast, Mg cations are octahedrally substituted for Al cations At page 352, it is stated that cracking activity is satisfactorily related to Bronsted acidity while it is difficult to find any relationship between the disproportionation activity and the acidic property.
In British Patent GB 1,265,152 ortho-alkylated phenols were prepared in about 52% yield using Fulmont at 300.degree. C. with a small amount of sulfuric acid In German Patent 2,552,175, KSF was the catalyst and about 15% para-product was formed.
There is a review of the use of pillared, cation-exchanged and acid-treated montmorillonite as catalysts for certain organic reactions by J.M. Adams et al., J. Inclusion Phenomena, 5, 663 (1987), Applied Clay Science, 2, 309 (1987). These clays display Bronsted and Lewis acid activities. It is noted that while some cationic species ar stable in solution over a wide concentration and pH range, others are not, particularly solutions containing aluminum. It is noted that it is difficult to ensure a reproducible Al.sup.3+ clay and moreover, since workers have used slightly different exchanging and washing procedures, a comparison between related experiments is hindered. Commercial acid-treatment is carried out using concentrated hydrochloric, sulphonic or phosphoric acids. The concentration of the acid and the time of the treatment is variable. Sometimes the excess acid is removed by washing, whereas in other products this is not the case. Therefore there is a great variety in the type and activity of acid-treated clays.
Montmorillonites have been used as catalysts for the reaction of straight chain alk-1-enes to ethers, and for alkenes plus alcohols. In the latter, primary alcohols gave high yields, secondary less and tertiary alcohols only trace amounts. The Al.sup.+3 clays have efficiencies of one third to one half of Amberlyst.RTM. 15 in reactions of this type without solvent or using 1,4-dioxane.
The acid-treated clay K-306 can be used to convert methanol and ammonia to methylamines. Acid-treated clays have also been used to convert cumene hydroperoxide to phenol and acetone.
Of the known processes for producing alkylphenols, generally the processes require two stages for cooling and recycling and many of the catalysts are not stable at high temperatures. In addition, it is often difficult to obtain a high para- to ortho- ratio or to obtain, in the case of nonylphenol synthesis more monononylphenol relative to dinonylphenol and from the art it would appear that conversions of about 80% are about the most which could be expected in any process to prepare alkylphenols.
It would be a distinct advance in the art if alkylphenols such as nonylphenols and particularly para-nonylphenols could be prepared in one step with conversion of nonene as high as 97%. It would be particularly desirable if the catalyst exhibited high thermal stability. Such a process would be especially attractive commercially if the system were operated adiabatic, since close temperature control, cooling and recycling make many processes considerably more expensive.
It is an object of the instant invention to provide a one-step process for the synthesis of alkylphenols in high yield and with almost complete conversion of olefin using a catalyst system which can operate under adiabatic conditions and exhibits stability even at elevated temperatures Another object is to obtain high selectivity while, at the same time, producing a high ratio of para- to ortho- alkylphenol.